A presently-existing missile launch trailer is equipped with four outriggers or jacks powered by electric motors for raising the trailer off its road wheels. The outrigger jacks include ground-engagement pads or disks that apply downward pressure on the ground, to thereby lift the trailer bed away from the ground surface. Preferably the lift-away action is continued until the road wheels substantially clear the ground surface; this transfers the trailer weight onto the pads and thereby reduces any tendency of the trailer to roll from its designated position. When the trailer is to be moved to a new site the jacks are actuated to lower the trailer to a condition in which it is supported by its road wheels (and a towing tractor attached thereto by a "fifth wheel" connection).
Each of the four outrigger jacks must be energized for two-directional movement, either up or down, in accordance with the desires of the human operator. Each jack (or group of jacks) must be capable of energization independently of the other jacks so that the vehicle (trailer) can assume a substantially level attitude irrespective of different terrain slopes and contours. The "level attitude" requirement poses a "human indecision" problem during the trailer set-up period; the human operator is sometimes apt to make an incorrect switch selection that requires subsequent corrective action on his part. Such action could unduly delay total elapsed time to achieve trailer "lift-off" and attainment of a substantially level attitude. In some situations a long elapsed time could be detrimental to missile launch performance.
The present invention provides a manual controller which incorporates separate joy sticks for up and down movements. Each joy stick is restricted to tilting or rocking motions in four distinct directions for actuating selected ones of the jack-control switches. A pendulum-type "level" indicator is associated with the joy sticks to help the human operator select the "correct" direction of joy stick movement. In general, the invention seeks a controller structure that will minimize the "human indecision" problem.